Prolactin Effect On B Cell Line Of Patients With Systemic Lupus Erythematosus And Related Intracellular Signal Transduction Pathway

Aim: To investigate proalctin effect on B lymphocytes from SLE patients.Methods: The effects of human prolactin on EB-virus transformed peripheral B cell lines obtained from a lupus patient as well as a healthy control were studied. Receptors for prolactin at mRNA levels were tested using RT-PCR analysis. Both cell lines were randomly divided into 6 groups. Being stimulated with either prolactin alone at two different levels (20 ng/ml or 100 ng/ml) or combined with recombinant interleukin-2 (r-IL-2), cell proliferation rate and the supernatants Ig concentrations were tested by MTT and ELISA, respectively. Levels of phosphorylated signal transducer and activator of transcription (Stat)5 were tested by western-blot assay to investigate the possible intracellular signal transduction pathway mediated by prolactin.Results: The level of mRNA for prolactin receptor showed no significant difference in the two cell lines. Of the two cell lines investigated, proliferation rate changes showed paralleled trends with those of spontaneous Ig production after stimulation. The physiological concentration of prolactin (20 ng/ml) did not stimulate either cellproliferation rate or the Ig concentrations. Of note, prolactin alone at 100 ng/ml could significantly induced proliferation and Ig production in SLE B cell line, while prolactin at 100 ng/ml could not stimulate the healthy control cell line. When combined with IL-2, prolactin enhanced the efficacy of IL-2 in the stimulation of SLE B cell. In contrast, prolactin inhibited the IL-2 efficacy in stimulation of the control cell. Trends of level of phosphorylated Stat5 were well correlated with those of proliferation rate and Ig production.Conclusion: High concentration of PRL can induce proliferation and Ig production in SLE B cell line and enhance the efficacy of IL-2, which supports the role of prolactin in the pathogenesis of SLE...